Butterfly valve



FIG. 1 is a front view of a butterfly valve showing our new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a front perspective view thereof; and,

FIG. 8 is a rear perspective view thereof.

The broken lines in the drawings are for the purpose of illustrating portions of the butterfly valve which form no part of the claimed design. 

CLAIM The ornamental design for a butterfly valve, as shown and described. 